Thin film resistors and methods of manufacture

Abstract

A method of forming a semiconductor structure includes: forming a resistor over a substrate; forming at least one first contact in contact with the resistor; and forming at least one second contact in contact with the resistor. The resistor is structured and arranged such that current flows from the at least one first contact to the at least one second contact through a central portion of the resistor. The resistor includes at least one extension extending laterally outward from the central portion in a direction parallel to the current flow. The method includes sizing the at least one extension based on a thermal diffusion length of the resistor.

What is claimed: 
     
       1. A method of forming a semiconductor structure, comprising:
 forming a resistor over a substrate; 
 forming at least one first contact in contact with the resistor; and 
 forming at least one second contact in contact with the resistor, 
 wherein the resistor is structured and arranged such that current flows from the at least one first contact to the at least one second contact through a central portion of the resistor; 
 the resistor comprises at least one extension extending laterally outward from the central portion in a direction parallel to the current flow; and 
 the forming the resistor comprises sizing the at least one extension based on a thermal diffusion length of the resistor wherein the resistor comprises a resistor material and the thermal diffusion length of the resistor is calculated based on a thermal diffusivity of the resistor material. 
 
     
     
       2. The method of  claim 1 , wherein the forming the resistor comprises forming the resistor over an insulator layer over the substrate. 
     
     
       3. The method of  claim 2 , wherein the sizing the extension comprises sizing the at least one extension based on the thermal diffusion length of the resistor, a thermal diffusion length of the insulator layer, and a thickness of the insulator layer. 
     
     
       4. The method of  claim 1 , wherein:
 the substrate is comprised in a silicon on-insulator (SOI) wafer; 
 the SOI wafer comprises a buried insulator layer on the substrate and a silicon film on the buried insulator layer; and 
 the forming the resistor comprises forming a polysilicon resistor on an insulator layer that replaces a portion of the silicon film. 
 
     
     
       5. The method of  claim 1 , wherein:
 the substrate is comprised in a silicion-on-insulator (SOI) wafer; 
 the SOI wafer comprises a buried insulator layer on the substrate and a silicon film on the buried insulator layer; and 
 the forming the resistor comprises forming a diffused resistor in the silicon film. 
 
     
     
       6. The method of  claim 1 , wherein the forming the resistor comprises forming a refractory metal resistor in a wiring level over the substrate. 
     
     
       7. The method of  claim 1 , wherein the substrate comprises a bulk semiconductor substrate, and the forming the resistor comprises:
 forming a trench in a top surface of the bulk semiconductor substrate; 
 filling the trench with insulator material; and 
 forming a polysilicon resistor on the insulator material. 
 
     
     
       8. The method of  claim 1 , wherein the substrate comprises a bulk semiconductor substrate, and the forming the resistor comprises:
 forming a layer of gate dielectric material on a top surface of the bulk semiconductor substrate; 
 forming a polysilicon resistor on the layer of gate dielectric material. 
 
     
     
       9. The method of  claim 1 , further comprising forming a heat sink over the central portion of the resistor. 
     
     
       10. The method of  claim 9 , further comprising forming at least one heat sink contact extending from the heat sink to the substrate. 
     
     
       11. The method of  claim 1 , further comprising:
 forming at least one silicide contact on the resistor, wherein the at least one silicide contact directly contacts one of the at least one first contact and the at least one second contact; and 
 forming silicide on the at least one extension. 
 
     
     
       12. The method of  claim 11 , further comprising forming a blocking structure between the at least one silicide contact and the silicide on the at least one extension, such that the silicide on the at least one extension does not directly contact the at least one silicide contact. 
     
     
       13. The method of  claim 1 , wherein:
 the at least one extension comprises a wrap around portion that wraps around an end of the central portion of the resistor; and 
 there is a gap between the wrap around portion and the central portion of the resistor. 
 
     
     
       14. The method of  claim 1 , wherein the at least one extension is formed in a same plane as the central portion of the resistor. 
     
     
       15. The method of  claim 1 , wherein the thermal diffusivity of the resistor material is calculated based on a thermal conductivity of the resistor material, a mass density of the resistor material, and a heat capacity of the resistor material. 
     
     
       16. The method of  claim 15 , wherein the sizing the at least one extension comprises sizing the at least one extension based on the thermal diffusion length of the resistor, a thermal diffusion length of the insulator layer, and a thickness of the insulator layer. 
     
     
       17. The method of  claim 16 , wherein the insulator layer comprises an insulator material and the thermal diffusion length of the insulator layer is calculated based on a thermal diffusivity of the insulator material. 
     
     
       18. A method of fabricating a semiconductor structure, comprising:
 forming a resistor over an insulator layer over a substrate; 
 forming a first silicide contact at a first location on the resistor; 
 forming a second silicide contact at a second location on the resistor; 
 forming a first contact over and contacting the first silicide contact; 
 forming a second contact over and contacting the second silicide contact; 
 forming a first interconnect over and contacting the first contact; and 
 forming a second interconnect over and contacting the second contact; 
 wherein the second location is different than the first location and the resistor is structured and arranged such that current flows from the first contact to the second contact through a central portion of the resistor; 
 the resistor comprises extensions extending laterally outward from the central portion in a direction parallel to the current flow; and 
 the extensions are formed in a same plane as the central portion. 
 
     
     
       19. The method of  claim 18 , wherein the forming the resistor comprises sizing the at least one extension based on a thermal diffusion length of the resistor, a thermal diffusion length of the insulator layer, and a thickness of the insulator layer.